Method for operating a contactor

Abstract

A method for operating a contactor ( 10 ) is described, wherein the contactor ( 10 ) comprises at least two contacts ( 18, 20, 22 ) electrically conductively connected to one another in a closed state of the contactor ( 10 ), having the method steps of partially charging an DC link capacitance ( 103 ) in electrical contact with the contactor ( 10 ) and closing the contactor ( 10 ).

The invention claimed is: 
     
       1. A method for operating a contactor ( 10 ), wherein the contactor ( 10 ) comprises contacts ( 18 ,  20 ,  22 ) electrically conductively connected to one another in a closed state of the contactor ( 10 ), the method comprising the following steps:
 a) partially charging, via a control unit ( 140 ), a DC link capacitance ( 103 ) in electrical contact with the contactor ( 10 ); 
 b) closing, via the control unit ( 140 ), the contactor ( 10 ); 
 c) producing an arc while closing the contactor to clean a surface of the contacts; and 
 d) detecting whether the contacts ( 18 ,  20 ,  22 ) of the contactor ( 10 ) make contact with a contact resistance that is above a predefined value when the contactor ( 10 ) is closed, and carrying out method steps a) and b) only when the contact resistance is above the predefined value. 
 
     
     
       2. The method according to  claim 1 , wherein the DC link capacitance ( 103 ) is partially precharged up to a value of 60-95% of a battery voltage of a battery connected to the contactor. 
     
     
       3. The method according to  claim 1 , wherein the DC link capacitance ( 103 ) is partially precharged by means of a precharging device, comprising a precharging contactor ( 103 ) and a precharging resistor ( 104 ), an electron pump or a combination of a semiconductor switch with a downstream electrical resistor. 
     
     
       4. The method according to  claim 1 , wherein, in method step b), the current flowing through the contactor ( 10 ) is measured or the time until the DC link capacitance exceeds a voltage threshold value is measured. 
     
     
       5. The method according to  claim 4 , wherein the contact resistance at a current intensity in a range of from ≥100 A to ≤200 A is in a range of from ≥0.1 mΩ to ≤2 mΩ. 
     
     
       6. The method according to  claim 1 , further comprising moving one of the contacts between an open position and a closed position. 
     
     
       7. The method according to  claim 6 , further comprising supplying a voltage to a coil surrounding a limb of the contact bridge. 
     
     
       8. The method according to  claim 7 , wherein supplying the voltage to the coil moves one of the contacts between the open position and the closed position. 
     
     
       9. An electrical circuit system comprising:
 a control unit ( 140 ); and 
 at least one contactor ( 10 ) having at least two contacts ( 14 ,  16 ,  20 ) that can make contact with one another in a closed state of the contactor ( 10 ), wherein the contactor ( 10 ) is controllable via the control unit ( 140 ), and wherein the control unit ( 140 ) is configured to: 
 a) partially charge a DC link capacitance ( 103 ) in electrical contact with the contactor ( 10 ); 
 b) close the contactor ( 10 ) to produce an arc that cleans a surface of the at least two contacts; and 
 detect whether the contacts ( 18 ,  20 ,  22 ) of the contactor ( 10 ) make contact with a contact resistance that is above a predefined value when the contactor ( 10 ) is closed, and carry out steps a) and b) only when the contact resistance is above the predefined value. 
 
     
     
       10. The electrical circuit system according to  claim 9 , wherein said electrical circuit has an DC link capacitance ( 103 ), which is configured to connect to a battery via a precharging device, wherein the precharging device comprises a precharging contactor ( 103 ) and a precharging resistor ( 104 ), an electron pump or a combination of a semiconductor switch with a downstream electrical resistor. 
     
     
       11. The electrical circuit system according to  claim 9 , wherein at least one of the two contacts is a contact bridge moveable between an open position and a closed position. 
     
     
       12. The electrical circuit system according to  claim 11 , wherein the arc is produced when the contact bridge is moving from the open to the closed position. 
     
     
       13. The electrical circuit system according to  claim 12 , further comprising a limb extending from the contact bridge and surrounded by a coil. 
     
     
       14. The electrical circuit system according to  claim 13 , wherein the contact bridge moves between the open position and the closed position when a voltage is supplied to the coil.